is there any particular reason why so many CAPs have such high BSTs?
More to the point, CAPs have to compete with OU mons, who have gotten better and better every gen. So, we can either decide that every new CAP is a legend or near enough (which adds a bunch of extra baggage like exact BSTs, locking our ability, etc.), or we can just make a regular-ish Pokemon and not really worry about our BST looking "off".